The engineering field often presents situations where it is necessary to couple two components together in a manner whereby relative axial movement is not desired while rotational movement and axial adjustment are required.
One means whereby this function is achieved is the conventional turnbuckle in which the axial adjustment is achieved by a threaded eye bolt located in a threaded aperture at one end of the main body while rotational movement is achieved by rotatably securing fixing means at the opposite end of the body.
The conventional turnbuckle is in many cases quite satisfactory. It does not, however, lend itself to use in situations where compactness is a prime requirement.
Couplings of the general type to which this invention relates fall into two classes, namely the high and the low class couplings. The high class couplings are usually produced for use in situations where high loading capability together with relatively low rotational friction losses is a specific requirement. For this reason the high class couplings are complicated and expensive. The low class couplings are relatively simple and inexpensive to manufacture but cannot contend with high loads without suffering the undesirable high rotational friction losses. Thus, it will be seen that there is a specific requirement for a pivotal coupling which is suitable for use in both high loading and low loading situations and is economical to produce.